Swim fin

ABSTRACT

A swim fin that changes down kick force is revealed. The swim fin worn over the foot to aid movement through the water includes a footpocket and a flat fin blade. The flat fin blade extends from the front part of the footpocket and has an upper blade surface and a lower blade surface. At least one blade surface is disposed with two fin ribs arranged symmetrically. By being embedded with heavy objects inside the fin rib, the weight of the swim fin is increased so as to increase the force of the swim fin acted on the water by kicking. This favors down kick of legs and the propelling force of kick is increased so that the user is allowed to move faster in the water with the swim fin.

BACKGROUND OF THE INVENTION

The present invention relates to a swim fin, especially to a swim fin that changes down kick force by weight objects embedded in ribs of flat fin blades so that users overcome the buoyant force more easily by kicking downward with the swim fin and the propelling power to push users through the water is increased.

A fin that is worn over the foot to aid movement for swimmers or divers through the water in water sports activities includes a footpocket and a flat fin blade. Generally, the swim fin has two types-mono-fin and bio-fin.

The mono-fin consists of a single footpocket for both feet while the bio-fin type includes a pair of footpockets respectively for each foot. That means the footpocket of the bio-fin is only for a single foot. Generally, the fin is made from plastic or float rubber so that the weight of the fin is quite light. Thus due to buoyant force, the user needs to apply larger force through their feet to kick down on the water. When the fin blade is wider or longer, the user applies larger force to kick with their legs and the kick frequency is reduced (lower). Once the fin blade is shorter or narrower, the user applies less force to kick with their legs and the kick frequency is increased, Thus users can choose various types of swim fins with different weight and length (width) according to the force applied to the kicking legs. However, the weight and length of the blade are fixed and are unable to be fine-adjusted or modified according to individual needs.

SUMMARY OF THE INVENTION

Therefore it is a primary object of the present invention to provide a swim fin that is worn over users' feet to aid movement through the water consists of a footpocket and a flat fin blade. The footpocket can be a mono-fin type or a pair for each foot to form a bio-fin type. The flat fin blade is formed by extension of front part of the footpocket and having an upper blade surface as well as a lower blade surface. At least one blade surface is disposed with two fin ribs arranged symmetrically. By being embedded with heavy objects inside the fin rib, the weight of the fin is increased so as to increase the force of the fin acted on the water by kicking. This favors down kick of users legs and the propelling power of kick is increased so that users are allowed to move faster in the water.

It is another object of the present invention to provide a swim fin in which a plurality of cutting lines is disposed on a blade surface of the flat fin blade, corresponding to a tail line on the flat fin blade. Thus the length of the flat fin blade is adjusted by cutting along the cutting line so as to match users' individual requirement. The user can choose optimum length suitable for their own force and kick frequency.

It is another object of the present invention to provide a swim fin that is a mono-fin that includes a single footpocket for both feet or a bio-fin that includes a pair of footpockets respectively for each foot.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an embodiment of a mono-fin according to the present invention;

FIG. 2 is an explosive view of an embodiment of a mono-fin according to the present invention;

FIG. 3 is a top view of the embodiment in FIG. 1;

FIG. 4 is a schematic drawing showing a flat fin blade being cut with shorter length of the embodiment in FIG. 3;

FIG. 5 is a perspective view of an embodiment of bio-fin according to the present invention;

FIG. 6 is an explosive view of an embodiment of a bio-fin according to the present invention;

FIG. 7 is a top view of the embodiment in FIG. 5;

FIG. 8 is a schematic drawing showing a flat fin blade being cut with shorter length of the embodiment in FIG. 7;

FIG. 9A is a partial enlarged view of a steplike cutting line on the blade surface;

FIG. 9B is a partial enlarged view of a slot-like cutting line on the blade surface.

DETAILED DESCRIPTION OF THE PREFFERED EMBODIMENT

Refer from FIG. 1 to FIG. 5, a swim fin 1 of the present invention is worn over feet to aid movement through the water and is formed by a footpocket 10 and a flat fin blade 20. The footpocket 10 is to receive users' feet so that users can apply force to the legs for moving the fin 1 and propelling users through the water. Moreover, the footpocket 10 can be a single one for both feet or a pair of swim fins respectively having a footpocket for each foot, as shown in FIG. 5 (only one swim fin of the pair). The bio-fin means the right foot and the left foot respectively is worn with a swim fin.

Refer from FIG. 1 to FIG. 8, the flat fin blade 20 is formed by the footpocket 10 extending forward and having an upper and a lower blade surfaces 21. At least one of the blade surfaces 21 is disposed with two symmetrical right and left fin ribs 22. In this embodiment, there are four fin ribs 22, as shown in FIG. 2 & FIG. 5. The shape of the fin rib 22 is not restricted and is designed according to shape of the swim fin 1. Moreover, the two fin ribs 22 on the blade surface 21 respectively are arranged with a slot 221. The shape and the number of the slot 221 are not limited and are designed according to shape of the fin rib 22. The slot 221 is used to load heavy objects 22 such as lead block(ingot) so as to increase weigh of the swim fin 1 and the kick down force is increased by the swim fin 1. Furthermore, the heavy objects 222 inside the fin rib 22 can be replaced by other objects according to users needs. For example, the heavy objects 222 can be a plurality of blocks with certain weight. The number of the blocks put into the slot 221 depends on users requirements. Or the structure can be designed into a fixed type that is unable to change weight of the heavy objects 222, as shown in FIG. 6. The heavy objects 222 can be put into a mold and integrated with the swim fin 1 by injection molding. In addition, the swim fin 1 is made from light weight material such as plastic or float rubber so that the user is difficult to kick and press down due to buoyant force of water. And the force applied to the legs is increased so that the kick frequency is reduced and the legs jerk from fatigue. By the heavy objects embedded in the fin rib 22, the weight of the swim fin 1 is increased so that the buoyant force is easily to be overcome, the kick frequency is further increased and the propelling force is improved.

The weight of the heavy objects 222 in the fin rib 22 of the swim fin 1 can be changed and adjusted according to users needs. When the user feels it's heavy to kick down through the water with the swim fin 1, the user can change the weight of the swim fin 1 by replacement of the heavy objects 22 with certain weight so as to get the swim fin 1 with optimum weight. In use, the user is easy to kick up and down, increasing the kick frequency and the propelling force.

A tail line 23 is arranged on a front part of the lower blade surface 21. A plurality of cutting lines 24 is disposed on the lower blade surface 21, corresponding to the tail line 23. By cutting along the cutting lines 24, the length of the blade surface 21 can be adjusted, as shown in FIG. 3 & FIG. 7. The cutting lines 24 can be designed into a structure with a step height difference such as steplike or slot-like structure for increasing friction between the blade surface 21 of the swim fin 1 and water, as shown in FIG. 9A & FIG. 9B. The shape of the cutting line 24 is not restricted. For example, it can be streamlined that looks like a tail fluke of whales. Moreover, the cutting lines 24 can be spaced at an equal distance (in FIG. 3) or unequal distance(in FIG. 7). In practice, the optimum length and width of the blade surface vary according to the users. Refer to FIG. 4 & FIG. 8, the length of the swim fin 1 according to the present invention can be modified directly in accordance with the user's requirement. The length is adjusted by cutting along the cutting line 24. As shown in FIG. 4 & FIG. 8, the user chooses one of the cutting lines 24 to cut so as to shorten the length of the swim fin 1. In practice, it's better to cut from the foremost cutting line 24. Once the length still needs to be adjusted, cut along the next cutting line 24 so as to get optimum length of the blade surface for the user.

Additional advantages and modifications will readily occur to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details, and representative devices shown and described herein. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents. 

1. A swim fin comprising: a footpocket worn over feet of users; and a flat fin blade extending from front part of the footpocket and having an upper blade surface as well as a lower blade surface while at least one blade surface is disposed with two fin ribs arranged symmetrically and the two fin ribs are mounted with slots for loading heavy objects; wherein when the slot on the fin rib of the blade surface is loaded with heavy objects, weight of the swim fin is increased so as to increase kick down force of the swim fin.
 2. The device as claimed in claim 1, wherein two fin ribs are arranged correspondingly on left and right sides of the upper blade surface and the lower blade surface of the flat fin blade.
 3. The device as claimed in claim 1, wherein the heavy object is lead block.
 4. The device as claimed in claim 1, wherein the heavy objects include a plurality of blocks with certain weight and a certain number of the blocks are put into the slot of the fin rib.
 5. The device as claimed in claim 1, wherein the heavy object is integrated into the fin rib.
 6. The device as claimed in claim 1, wherein the footpocket is a single footpocket for both feet so as to form a mono-fin type swim fin.
 7. The device as claimed in claim 1, wherein the footpocket is a footpocket for each foot so as to form a bio-fin type swim fin.
 8. The device as claimed in claim 1, wherein a tail line is disposed on a front end of the lower blade surface and a plurality of cutting lines with intervals is disposed on the lower blade surface, corresponding to the tail line.
 9. The device as claimed in claim 8, wherein the cutting line on the lower blade surface is a structure with a step height.
 10. The device as claimed in claim 8, wherein the structure with the step height of the cutting line on the lower blade surface is a steplike or slot-like structure.
 11. The device as claimed in claim 8, wherein the cutting line on the lower blade surface is streamlined that looks like a tail fluke of whales.
 12. The device as claimed in claim 8, wherein the plurality of cutting lines are arranged apart at an equal distance.
 13. The device as claimed in claim 8, wherein the plurality of cutting lines are spaced at an unequal distance. 